The performance reportedly used the same technology that enabled Mariah Carey to perform a concert in five cities simultaneously. Executing the Carey illusion relied on both modern day techniques and an old magician’s trick dating back to the 19th Century.

First, a video was composed by New York SFX company MPC using a mixture of live footage, wire-framing, and CGI. This was then fed into Musion’s holographic technology, which projects the image onto a special foil. The foil is based on principles set out in the old magician’s illusion Pepper’s Ghost, which trick audiences into thinking they’re viewing a person or object rather than a simple reflection. By using a lightweight foil which mimics the properties of semi-transparent glass, Musion is able to extend the concept’s scale without limiting the efficacy of the illusion.(via)